Secondary mania develops in as many as 9% of persons with traumatic brain injuries. The treatment of posttraumatic mania is not well defined, and agents traditionally used for the treatment of idiopathic manic episodes may not be well suited for use among individuals with traumatic brain injuries. Atypical antipsychotics are indicated for the treatment of idiopathic bipolar disorder, and have been used for other purposes among individuals with posttraumatic neuropsychiatric disturbances. This article offers the first description of the treatment of posttraumatic mania using the atypical antipsychotic quetiapine. Beneficial effects of this agent on posttraumatic mania, cognitive impairments, and functional disability in the subacute post-injury period are described. Possible mechanisms of action are discussed and the need for additional investigation of quetiapine for posttraumatic mania is highlighted.